The quaternary sector of an economy refers to the portion of a workforce comprised of highly skilled individuals who are proficient in information services or fields based on knowledge. As an emerging characteristic of the post-industrial economies that developed in the late 20th century, large transnational companies grew to become providers or producers of information technology. This created a need for individuals possessing skills and knowledge in areas such as research and development, education, consulting, financial planning and data collection.
The term quaternary sector sometimes describes the areas of culture, media and government and also includes, by some definitions, the entertainment industry. In a well-developed country, the quaternary sector grows as a greater number of skilled workers are necessary to meet the growing needs of the service sectors. This is an indicator of an economy moving into the post-industrial phase as it also moves away from manufacturing and the production of raw materials.
According to the 20th-century British and Australian economist Colin Clark, an economy consists of three main sectors, with the quaternary and quinary sectors developing out of them as the economy progresses. Clark's sector model categorizes an economy into the primary sector, which produces raw materials, the secondary sector, which handles manufacturing, and the tertiary sector, which is the service industry. As the economy progresses, the information-based quaternary sector develops. The fifth component, the quinary sector, refers to human services.
In the United Kingdom, which has a well-developed economy, the tertiary and quaternary sectors employ more than 70 percent of the workforce.